Generally, a fuel cell stack mounted in a fuel cell vehicle includes a plurality of stacked fuel cells. The fuel cell stack is an apparatus for the generation of electricity through the electrochemical reaction of hydrogen and oxygen while producing water.
In this case, each unit cell of the fuel cell stack includes a membrane-electrode assembly (MEA), which is disposed in the middle thereof. The MEA includes a polymer electrolyte membrane, and catalyst layers coated on both sides of the polymer electrolyte membrane which function as an anode electrode and a cathode electrode, respectively.
Furthermore, gas diffusion layers (GDLs) are disposed on the outer sides of the MEA, that is, outside of the catalyst layers. Separators are disposed outside of the gas diffusion layers while including channels to supply gas to the reaction, and to discharge water produced by the reaction.
As a result, the unit cell of the fuel cell may include one MEA, two GDLs, and two separators. Furthermore, several tens to several hundred unit cells may be stacked to constitute a fuel cell having a desired scale.
In the unit cell of such a fuel cell, each GDL should allow gas to be uniformly transferred to the MEA while allowing water produced at the MEA to be smoothly discharged through the channels.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.